Ventricular fibrillation, catecholamine- resistant septic / hypovolaemic or post-CPB vasodilatory shock.
Increases SVR + MAP, decreases CI, PAP usually unchanged or decreased. Urine output increased / no change.
1 ampoule Pitressin = arginine vasopressin 20U
Central iv. administration preferable.
Endotracheal / intraosseous also effective, dose as for iv bolus.
1U/ml in 60ml syringe. (3 ampoules vasopressin in N/saline)
Refractory shock: (Hypotension despite adequate preload + catecholamines, exclusion of tamponade / tension pneumothorax / ionised Ca++ < 0.8mmol/l) Consider bolus 1-10U for severe hypotension. Commence infusion at 0.1U / min., wean down to 0.02U/min then stop.
Hypovolaemic cardiac arrest: bolus 40U.
Infuse at 0.1U/ min. initially, titrate downwards as tolerated following catecholamine reduction to 0.02U/min before ceasing.
Infuse at 0.04U/min. Higher doses may be associated with increased side effects. Titrate down as tolerated.
Possibly less common in shock than in other clinical settings (as may be vasopressin deficient).
Gastric hypoperfusion: bowel ischaemia / raised liver enzymes / reduced platelet count.
Higher doses: myocardial ischaemia. Hyponatraemia. Cutaneous necrosis from extravasation. Allergy.